WO2005040246A1

WO2005040246A1 - Acyloxy acetic acid polymer and method for producing same

Info

Publication number: WO2005040246A1
Application number: PCT/JP2004/015852
Authority: WO
Inventors: Atsushi Wada; Tomonori Ohashi
Original assignee: Nippon Kasei Chemical Company Limited
Priority date: 2003-10-29
Filing date: 2004-10-26
Publication date: 2005-05-06
Also published as: JPWO2005040246A1; EP1679331A4; EP1679331A1; US20070110701A1

Abstract

Disclosed is an acyloxy acetic acid polymer which enables to economically synthesize an acyloxy acetic acid, a glycolic acid, esters thereof or glycolides more simply under milder conditions. The acyloxy acetic acid polymer can be used as a biodegradable polymer. The acyloxy acetic acid polymer is represented by the general formula (1) below. In the preferred embodiment of the present invention, the acyloxy acetic acid polymer is obtained by reacting a formaldehyde compound, carbon monoxide, and an organic carboxylic acid or its derivative in the presence of an acid catalyst. (1) (In the general formula (1), R1 and R2 independently represent a hydrogen atom or a lower alkyl group which may be branched, and n represents an integer of not less than 5.)

Description

Specification

Acyloxyacetic acid polymer and method for producing the same

Technical field

The present invention relates to a novel acyloxyacetic acid polymer and a method for producing the same.

Background art

[0002] Acetoxyacetic acid, which has a high utility value among acyloxyacetic acids, is used as a raw material for synthesis when producing various chemical products such as agricultural chemicals and surface treatment agents, and is an important compound in the chemical industry. Glycolic acid is an important compound as an industrial intermediate, as a raw material for polymers and as an additive, in addition to direct uses such as chemical detergents. The following methods are known as methods for synthesizing these compounds!

[0003] Acetoxyacetic acid is synthesized by heating ethyl ethyl glycolate and acetic acid together with a small amount of sulfuric acid in benzene to remove the generated water and ethyl acetate (for example, see Non-Patent Document 1). There is a method of reacting acetic acid and oxygen gas under high temperature and high pressure in the presence of three components of metal iodide, metal oxide (or metal acetate) and iodine (for example, see Patent Document 1).

[0004] In the former method, the starting material ethyl glycolate is an irritating and flammable substance, and is easy to handle and expensive. In the latter method, the catalytic activity is not exhibited unless the three components coexist! ヽ Since the separation operation between the catalyst and the product is complicated, the cost is high, and the yield of the product acetoxyacetic acid is high. Is low (the yield of acetoacetic acid in the examples: 1% by weight).

[0005] Using an aliphatic aldehyde and carbon monoxide as catalysts, a SiO ZA1 O molar ratio of at least 10

2 2 3

There has been proposed a method of obtaining a hydroxycarboxylic acid derivative by using 0 or more mordenite and reacting in a reaction medium (for example, see Patent Document 2). In addition, it is possible to synthesize acetoacetic acid as hydroxycarboxylic acid. Have been reported. However, in order to obtain a high yield of acetoacetic acid by this method, a temperature of 170-200 ° C.! When using highly toxic gases such as carbon monoxide, the reaction conditions are preferably mild. Furthermore, high silica type mordenite having a high molar ratio of SiO ZA1 O is usually used. Very expensive compared to mordenite.

[0006] Further, in the presence of a sulfate-supported metal oxide (sulfate-supported zirconia, sulfate-supported titer and sulfate-supported tin oxide) in a reaction medium, formaldehyde is converted to monoacid-based carbon dioxide. A method for synthesizing acetoacetic acid by reacting acetic acid and Z or acetic anhydride with acetic acid has been proposed, but it has not been reported that the target compound was specifically isolated (for example, see Patent Document 3).

[0007] In the case of glycolic acid and its ester, a mineral acid such as sulfuric acid, phosphoric acid or hydrochloric acid is used as a catalyst, and formaldehyde, water and carbon monoxide are reacted under high pressure to convert glycolic acid in one step. A method of producing glycolic acid by reacting formaldehyde, water and carbon monoxide in hydrogen fluoride under normal pressure in hydrogen fluoride (for example, see Patent Document 5) and the like (for example, see Patent Document 5) . These methods have problems such as the necessity of complicated operations for separating glycolic acid from the reaction solution, and thus cannot be said to be industrially excellent.

[0008] In addition, it has been reported that the reaction of formate, formaldehyde, and carbon monoxide in the presence of an acid catalyst slightly generates a condensed dimer in the reaction system (for example, Patent Document 6). In the report, the dimer formed has been hydrolyzed or alcoholyzed as it is, and no dimer has been isolated.

[0009] Non-Patent Document 1: Beilstein, 3, 233

Patent Document 1: JP-A-56-63941

Patent Document 2: JP-A-11-147042

Patent Document 3: JP 2001-335538 A

Patent Document 4: Japanese Patent Publication No. 53-44454

Patent Document 5: JP-A-51-13719

Patent Document 6: JP-A-56-122321

Disclosure of the invention

Problems to be solved by the invention

[0010] The present invention has been made in view of the above-mentioned circumstances, and has as its object a simpler and more mild process under the conditions of acyloxyacetic acid-glycolic acid and its esters and Dali. An object of the present invention is to provide an acyloxy acetic acid polymer which can be economically synthesized and can be used as a biodegradable polymer, and a method for producing the same.

Means for solving the problem

[0011] The present inventors have conducted intensive studies, and as a result of hydrolysis, synthesized acyloxyacetic acid and glycolic acid by hydrolysis, acyloxyacetic acid ester glycolide ester by alcoholysis, and glycolide by thermal decomposition. A novel acyloxyacetic acid polymer and a method for producing the same have been found and the present invention has been completed.

That is, a first gist of the present invention resides in an acyloxyacetic acid polymer represented by the following general formula (1).

[0013] [Chemical 1]

R ¹ ₃ CCO——, 0CH ₂ C0-/) —— _n OR ² (丄)

(In the general formula (1), each and R ² each independently represent a hydrogen atom or a lower alkyl group which may be branched, and n represents an integer of 5 or more.)

[0014] The second gist of the present invention is that a formaldehyde conjugate is reacted with carbon monoxide and an organic carboxylic acid or a derivative thereof in the presence of an acid catalyst to obtain an acyloxyacetic acid derivative. A method for producing an acyloxyacetic acid polymer represented by the general formula (1), comprising condensing the obtained acyloxyacetic acid derivative.

The invention's effect

The acyloxyacetic acid polymer of the present invention can produce acyloxyacetic acid / glycolic acid by hydrolysis, alcoholyl acetate / glycolic acid by alcoholysis, and glycolide by thermal decomposition. It can be used as a biodegradable polymer.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail. The acyloxyacetic acid polymer of the present invention is represented by the general formula (1). In the general formula (1), each of R ¹ and R ² is preferably a hydrogen atom or a C1-C6 lower alkyl group, more preferably a hydrogen atom or a C1-C4 atom. A hydrogen atom, and particularly preferably a hydrogen atom (in this case, the compound is an acetoacetic acid polymer). The degree of polymerization n is preferably 5 or more, more preferably 10 or more, and particularly preferably 25 or more. When n is 5 or more, the reaction system can be easily isolated, and when n is 10 or more, the solidification and isolation can be further facilitated, so that the handling becomes easy. The upper limit of the degree of polymerization n is usually 10,000.

The acyloxyacetic acid polymer of the present invention, for example, an acetoacetic acid polymer, has a glycolic acid content of usually 110 to 130% by weight and an acetoxy content of usually quantified by high performance liquid chromatography after hydrolysis with an alkali. 0.1-15% by weight. Its melting point is usually 120 ° C or higher. The weight average molecular weight is usually 500-580,000. The amount of diglycolic acid contained as an impurity in the polymer is preferably 1% by weight or less, more preferably 0.1% by weight or less.

The acyloxyacetic acid polymer of the present invention is preferably obtained by condensing an acyloxyacetic acid derivative. Examples of the acyloxyacetic acid derivatives mentioned here include acyloxyacetic acid, glycolic acid, oligomers of acyloxyacetic acid, oligomers of glycolic acid, and esters thereof.

The acyloxyacetic acid polymer of the present invention is obtained by reacting a formaldehyde compound, carbon monoxide, and an organic carboxylic acid or a derivative thereof in the presence of an acid catalyst. Are preferably obtained by condensation. In particular, an acyloxyacetic acid derivative obtained by reacting an organic carboxylic acid, an aldehyde compound and monocarboxylic acid in the presence of an acid catalyst is directly condensed without isolation, and is isolated as an acyloxyacetic acid polymer of the present invention. I prefer that. The following chemical formula is an example of the above series of reactions.

[0020] [Chemical 2] Solid acid catalyst

CH ₂ 0 + CO + CH ₃ COOH + H ₂ 0

Examples of the above acid catalyst include mineral acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, hydrofluoric acid, perchloric acid, nitric acid, sulfuric acid, hexafluorophosphoric acid, fluorosulfonic acid, and chlorosulfonic acid; Organic acids such as trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid; heteropolyacids such as keitungstic acid, phosphotungstic acid, and phosphomolybdic acid; boron trifluoride; Solid acids such as Lewis acids such as phosphorus fluoride and antimony pentafluoride, strongly acidic cation exchange resins, clay minerals, zeolites, solidified acids, inorganic oxides, inorganic salts, and composite oxides.

[0022] Strongly acidic cation exchange resins include styrene-divinylbenzene copolymers such as Amberlyst 15 (manufactured by Rohm and Nose Co.) and Diaion PK228 (manufactured by Mitsubishi Chemical), whose functional groups are sulfone groups. And a tetrafluoroethylene-based polymer such as Nafion (manufactured by DuPont). Examples of clay minerals and zeolites include montmorillonite, kaolinite, bentonite, halloysite, smectite, illite, permikulite, chlorite, sebiolite, attapulgite, polygoskeite, mordenite, etc., and especially acids such as hydrogen fluoride. It is preferable that the metal ion is exchanged with a hydrogen ion for exchangeable metal ions such as H-type zeolite. Examples of the solidified acid include those obtained by supporting an acid such as a heteropoly acid on a carrier such as activated carbon or silica. Considering the separation step of the final product, a strongly acidic cation exchange resin (sulfonic acid type cation exchange resin), which does not dissolve in the reaction system and is preferably a solid acid, is preferred.

In the present invention, the above-mentioned sulfonic acid type cation exchange resin is preferably used after being washed with an acid in advance. As an impurity in sulfonic acid type cation exchange resin by acid washing The sulfate groups contained therein can be easily removed, and an acyloxyacetic acid polymer having a reduced amount of sulfate groups can be obtained.

The above-mentioned acid washing is performed, for example, using an organic carboxylic acid described later as a raw material. The amount of the acid to be used is generally 11 to 10 times, preferably 2 to 5 times, as a weight ratio to the sulfonic acid type cation exchange resin. The temperature of the acid washing is usually 10-150 ° C, and the time is 0.5-10 hours. The acid washing is usually performed in a suitable container with stirring. By such acid washing, free sulfate groups present in the sulfonic acid type cation exchange resin can be removed, and an acyloxyacetic acid polymer having a reduced amount of sulfate groups can be produced.

[0025] The raw material aldehyde compound is not particularly limited as long as it is a compound that produces formaldehyde under the reaction conditions, such as paraformaldehyde, trioxane, and methylal, in addition to aqueous formaldehyde (formalin) and gaseous formaldehyde. Dear,. Two or more of these compounds may be used in combination. The organic carboxylic acid may be acetic acid, propanoic acid, butanoic acid, or a carboxylic acid having an unsaturated bond such as propiolic acid. The derivative of the organic carboxylic acid may be an ester or an anhydride. After the acyloxyacetic acid derivative of the present invention, which is the aforementioned acyloxyacetic acid derivative or a condensate thereof, can be used as an organic carboxylic acid derivative. The above organic carboxylic acids participate in the reaction and also have an effect as a reaction solvent. The amount used is usually from equimolar to 100-fold, preferably 115-fold, relative to the number of moles of formaldehyde used as a raw material (in the case of a compound that produces formaldehyde under the reaction conditions, the number of moles converted to formaldehyde). Is a mole. The same applies to the amount of the organic carboxylic acid derivative used.

[0026] A reaction solvent other than the above organic carboxylic acids may be added. The solvent used at this time can be used irrespective of polarity or non-polarity, but by using a solvent having a certain polarity, the acyloxyacetic acid conjugate can be obtained in high yield. Examples of the reaction medium include halogenated aliphatic hydrocarbons such as chloroform and dichloromethane, halogenated aromatic hydrocarbons such as benzene, aliphatic hydrocarbons such as hexane, cyclohexane, and methylcyclohexane, and benzene. And the like. [0027] The carbon monoxide is not only high-purity carbon monoxide, but also carbon monoxide mixed with an inert gas such as nitrogen or argon, hydrogen, Z or carbon dioxide. It can be used.

[0028] The reaction pressure is usually 10 to 200 kgZcm ² , preferably 50 to 100 kgZcm ² .

The reaction temperature is generally 80-200 ° C, preferably 100-150 ° C.

[0029] After completion of the reaction, the solid acid catalyst removed from the reaction system by filtration or the like can be recycled as a catalyst for the next batch. As a result, it is possible to reduce the catalyst cost.

[0030] Furthermore, the condensation of the acyloxyacetic acid derivative is preferably heat condensation, since a high degree of condensation can be achieved. The reaction temperature is usually 100-250 ° C, preferably 140-200 ° C. The reaction pressure may be normal pressure, but is usually 650-10 torr, preferably 200-lOtorr. The condensation reaction is performed while removing by-produced acetic acid and water under reduced pressure.

[0031] The desired acyloxyacetic acid polymer can be isolated as a solid by removing volatile components after the condensation reaction, and a solvent in which a polymer such as water is hardly soluble in the condensation reaction solution is used. After the addition, the mixture is precipitated by cooling, and can be separated by a usual method, for example, centrifugation.

[0032] In particular, the above-mentioned series of reactions using a solid acid catalyst employs a production facility including, for example, a formalin concentrator, a reactor containing a solid acid catalyst, an acetic acid concentrator, and a condensation reactor. Can be performed semi-continuously.

First, the formaldehyde conjugate concentrated in a formalin concentrator is dissolved in an organic carboxylic acid and continuously supplied to a reactor, where carbon monoxide is continuously supplied to carry out a reaction. . Then, only the reaction solution containing the acyloxyacetic acid derivative is taken out and supplied to the acetic acid concentrator, where the decompressed carbon monoxide generated and the organic carboxylic acid recovered by the concentration are circulated to the reactor, respectively. The concentrated solution of the acyloxyacetic acid derivative taken out of the acetic acid concentrator is supplied to a condensation reactor, and is heated and condensed under reduced pressure to obtain an acyloxyacetic acid polymer. Next, the condensation reaction solution is taken out and dehydrated under reduced pressure to recover an acyloxyacetic acid polymer.

[0034] In the above production method, the water concentration in the reactor is determined by the concentration in the formalin concentrator. Although it varies depending on the degree of shrinkage, the concentration of water in the recovered organic carboxylic acid, the amount of circulating water used, and the like, it is preferable to control these conditions and maintain them in a certain range. The water concentration in the reactor is usually 0 to 20% by weight, preferably 115% by weight. In addition, an acid anhydride such as acetic anhydride can be used as the organic carboxylic acid in order to easily control the water concentration in the reactor.

[0035] In the preferred embodiment of the present invention, the sulfate group content of the acyloxyacetic acid polymer is generally 300 ppm or less, preferably 500 ppm or less. If the sulfate group content of the acyloxyacetic acid polymer is high, the sulfate group should be contained as an impurity in useful compounds such as acyloxyacetic acid, glycolic acid, and glycolide obtained by hydrolysis, alcoholysis, and thermal decomposition. And there is a disadvantage that its use is limited.

The acyloxyacetic acid polymer of the present invention can synthesize acyloxyacetic acid / glycolic acid by hydrolysis, acyloxyacetic acid / glycolic acid ester by alcoholysis, and glycolide by thermal decomposition. For example, in the case of a glycolic acid ester, a methyl ester of glycolic acid can be easily obtained by reacting an acetoacetic acid polymer with, for example, a 10-fold amount of methanol in the presence of an acid catalyst as described above.

The method for analyzing the acyloxyacetic acid polymer obtained in the present invention is as follows.

[0038] The melting point was measured using a differential scanning calorimeter "DSC6200" manufactured by Seiko Instruments Inc.

In an aluminum pan, fill about 3g of sample, and in nitrogen 50mlZmin atmosphere, up to 30-260 ° C 10

The temperature is raised at a rate of ° CZmin, and the temperature of the endothermic peak is determined as the melting point.

[0039] The weight average molecular weight is measured by a GPC analyzer using hexafluoroisopropanol as a solvent. The measurement conditions are as follows: the column temperature is 40 ° C, the flow rate is lmlZmin, and a standard curve is prepared using standard PMMA (polymethyl methacrylate).

Example

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1:

Autoclave, acetic acid 90. 9 g, 80 weight ^_0/0 paraformaldehyde 22. 5 g, catalyst and to a cation exchange榭脂15g (Rohm and Nono chromatography, Inc., Ltd., "Amberlyst 15dry") to 15g ON After purging with carbon monoxide, the temperature was raised to 120 ° C., carbon monoxide was introduced to 80 kgZcm ² , and the mixture was reacted for 3 hours under stirring at 1200 rpm.

After the completion of the reaction, the pressure of carbon monoxide was released, and after purging with nitrogen, the reaction solution and the catalyst were separated by filtration, and the filtered catalyst was washed with acetic acid. The reaction filtrate and the catalyst washing solution were each sampled, hydrolyzed with an alkali, and analyzed using high performance liquid chromatography (LC-10A manufactured by Shimadzu Corporation). As a result, the glycolic acid yield based on the charged formaldehyde was 95 mol%. %. As a result of the analysis of this filtrate as by high performance liquid chromatography, as charged formaldehyde base, glycolic acid 8 mol ^_0/0, the Asetokishi acetate 6 1 mol%, Asetokishi acetate oligomer was 26 mol%.

The above filtrate was placed in a three-necked flask equipped with a stirrer, and heated in an oil bath to 140 ° C. under a reduced pressure of 100 torr to conduct a condensation reaction while distilling off acetic acid and water as by-products. After reacting at an internal temperature of 140 ° C for 4 hours, the reaction mixture was gradually cooled. When the internal temperature reached 90 ° C, 50 g of pure water was added, and the mixture was further cooled to room temperature. After filtering the produced acetoacetic acid polymer, it was dried with hot air at 60 ° C. for 24 hours to obtain 34.2 g of acetic acid acetic acid polymer. The obtained acetoxyacetic acid polymer had a glycolic acid content of 111% by weight and an acetoxy content of 9.8% by weight (after being hydrolyzed with an alkali and quantified by high performance liquid chromatography). The content was less than 0.1% by weight. The yield based on the charged formaldehyde was 83.2 mol%.

The melting point of the above-mentioned acetooxyacetic acid polymer was 125 ° C. as measured by DSC, and the weight average molecular weight was 4,000 (as a result of GPC measurement using hexafluoroisopropanol as a solvent. The degree of polymerization n calculated from this value was 68. Further, the filtrate after filtering the Asetokishi acetate polymer, was analyzed in the same manner as charged formaldehyde base, it contains glycolic acid of 10.5 mol ^_0/0, Other impurities such as diglycolic acid Was observed.

Example 2:

In Example 1, the ion-exchange resin used after filtering in Example 1 was used as a catalyst in a wet state, and acetic acid was used as a catalyst in the acetic acid solution collected by distillation in the condensation reaction in Example 1. The reaction was carried out in the same manner as in Example 1 except that the product purified by distillation was used. Steaming The water content of the fermented product was 0.1% by weight (Karl Fischer method), and peaks of impurities other than acetic acid were not particularly noticeable by analysis by gas chromatography. After completion of the reaction, the catalyst was filtered and analyzed in the same manner as in Example 1. As a result, the yield of glycolic acid based on the charged formaldehyde was 92 mol%, and it was confirmed that the catalyst could be used multiple times.

Example 3:

In Example 1, "Nafion" manufactured by DuPont was used as the ion exchange resin, the reaction pressure (partial pressure of carbon dioxide) was changed to 100 kgZcm ² , and the reaction temperature was changed to 130 ° C. The reaction was carried out as in 1. After the reaction was completed, the reaction mixture and the catalyst were separated by filtration, and the same analysis as in Example 1 was carried out. As a result, the yield of glycolic acid based on the charged formaldehyde was 95 mol%.

The above filtrate was charged into a three-necked flask equipped with a stirrer, heated to 200 ° C. under a reduced pressure of 50 torr in an oil bath, and subjected to a condensation reaction for 4 hours. After the reaction, the reaction solution was cooled and solidified as it was. This solid was pulverized with a pulverizer to obtain a powdered product of an acetoacetic acid polymer. As a result of analysis of this product, the glycolic acid content was 129% by weight and the acetoxium content was 1.0% by weight (determined by high performance liquid chromatography after hydrolysis with alkali), and the content of diglycolic acid as an impurity was 0%. .6% by weight and the yield based on the charged formaldehyde was 89 mol%. The melting point was 205 ° C as measured by DSC, and the weight-average molecular weight was 11,0000 (PMMA equivalent) as a result of GPC measurement using hexafluoroisopropanol as a solvent. The calculated degree of polymerization n was 189.

[0048] Reference example 1:

A methyl esterification reaction was carried out using the acetylethoxyacetic acid polymer obtained above. That is, a Hastelloy autoclave (capacity: 80 ml) was charged with the acetoacetic acetic acid polymer lg obtained in Example 3, 10 g of methanol, and 0.26 g of 96% by weight sulfuric acid as a catalyst, a magnetic stir bar was added, and the atmosphere was replaced with nitrogen. did. The autoclave was sealed and reacted at 100 ° C for 3 hours. After cooling, the reaction solution was analyzed by high performance liquid chromatography. As a result, it was found that 92 mol% was obtained based on the glycolic acid in the used acetoxyacetic acid polymer. Dalicolic acid methyl ester was produced at a rate.

Example 4: 150 g of a cation exchange resin ("Amberlyst 36wet" manufactured by Rohm and Nose Co.) was placed in a glass container, 750 g of acetic acid was further added as a washing solvent, and the mixture was purged with nitrogen, followed by stirring at 100 ° C for 5 hours. After cooling to room temperature, the cation exchange resin and the washing solvent were separated by filtration, and the cation exchange resin was washed again using 750 g of acetic acid under the same conditions as described above. The acetic acid solvent used in the heat washing was sampled, decomposed by microwave, evaporated to dryness with a carrier for ion chromatography, diluted, and the sulfate concentration in the solvent was measured by ion chromatography. The sulfate concentration in the first washing solvent was 170 ppm, and the sulfate concentration in the second washing solvent was 55 ppm.

Next, the reaction was carried out in the same manner as in Example 1 except that the cation exchange resin after the acid washing was used as a catalyst. That is, in Example 1, 19.6 g of 92% by weight paraformaldehyde and 30.8 g of a cation exchange resin catalyst (about 15 g on a dry basis) were used as the formaldehyde, and the reaction pressure (carbon monoxide partial pressure) was increased. The reaction was carried out in the same manner as in Example 1 except that the amount was changed to 70 kgZcm ² . After completion of the reaction, the catalyst was filtered and analyzed in the same manner as in Example 1. As a result, the yield of glycolic acid based on the charged formaldehyde was 92 mol%. The reaction solution (filtrate) from which the catalyst was filtered off was measured for the sulfate group concentration in the same manner as described above, and it was 140 ppm. As a result of the analysis of this filtrate as by high performance liquid chromatography, as formaldehyde-based narrowing specification, glycolic acid 6 mol ^_0/0, Asetokishi acetic acid 60 molar ^_0/0, Asetokishi acetate oligomer was 26 mol% .

[0051] The above filtrate was placed in a three-necked flask equipped with a stirrer, heated to 160 ° C in an oil bath under reduced pressure of 100 torr, and a condensation reaction was performed while distilling off acetic acid and water as by-products. After reacting at an internal temperature of 160 ° C for 4 hours, the mixture was gradually cooled. When the internal temperature reached 90 ° C, 50 g of pure water was added, and the mixture was further cooled to room temperature. The resulting acetoacetic acid polymer was filtered and dried with hot air at 60 ° C. for 24 hours to obtain 33. Og of the acetic acid acetic acid polymer. The obtained acetoxyacetic acid polymer had a glycolic acid content of 118% by weight and an acetoxy content of 9.8% by weight (after being hydrolyzed with an alkali and quantified by high performance liquid chromatography). The content was less than 0.1% by weight. The yield based on the charged formaldehyde was 85.4 mol%. The sulfate group content of the acetoacetic acid polymer was 470 ppm.

The melting point of the above-mentioned acetooxyacetic acid polymer was 170 ° C. as measured by DSC, The average molecular weight was 6,500 (in PMMA conversion) as a result of GPC measurement using hexafluoroisopropanol as a solvent, and the calculated polymerization degree n was 111. Further, the filtrate after filtering the Asetokishi acetate polymer, results were analyzed in the same manner as charged formaldehyde base, 6. contains glycolic acid of 5 mol ^_0/0, such as Other diglycolic acid An impurity peak was observed.

Claims

Claims [1] An acyloxyacetic acid polymer represented by the following general formula (1), [Chemical Formula 1] R13CCO—, 0CH2C0-^ / —— n OR2 (1)

(In the general formula (1), each of R ¹ and R ² is independently a hydrogen atom or a lower alkyl group which may be branched, and n represents an integer of 5 or more.)

[2] The acyloxyacetic acid polymer according to claim 1, which is obtained by condensing an acyloxyacetic acid derivative.

[3] The acyloxyacetic acid polymer according to claim 2, wherein the condensation is heat condensation.

[4] The acyloxy derivative according to any one of claims 2-3, wherein the acyloxyacetic acid derivative is obtained by reacting a formaldehyde compound with carbon monoxide and an organic carboxylic acid or a derivative thereof in the presence of an acid catalyst. Acetic acid polymer.

[5] A method of reacting a formaldehyde compound with carbon monoxide and an organic carboxylic acid or a derivative thereof in the presence of an acid catalyst to obtain an acyloxyacetic acid derivative, and then condensing the obtained acyloxyacetic acid derivative. A method for producing an acyloxyacetic acid polymer represented by the general formula (1).

[6] The production method according to claim 5, wherein a sulfonic acid type cation exchange resin washed with acid in advance is used as the acid acid catalyst.